Automatic air-discharge valve for blowing-engines.



No. 769.833. PATENTED SEPT. 13, 1904. A. K. RARIG.

AUTOMATIC AIR DISCHARGE VALVE FOR BLOWING ENGINES.

APPLICATION FILED MAR. 2. 1903.

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No. 769,833. v PATENTED SEPT. 18, 1904. A. K. RARIG.

AUTOMATIC AIR DISCHARGE VALVE FOR BLOWING ENGINES.

APPLIGATION FILED MAR. 2, 1903.

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jg lvwenfoz UNITED STATES Patented September 13, 1904.

PATENT OFFICE.

ALEXANDER K. RARIG, OF COLUMBUS, OHIO.

AUTOMATIC AIR-DISCHARGE VALVE FOR BLOWING-ENGINES.

SPECIFICATION forming part of Letters Patent No. 769,833, dated September 13, 1904:. Application filed March 2, 1903. Serial No. 145,732. (No model.)

ate automatically and under proper conditions and at the desired time. In engines of this character it is desirable to have the air-discharge valve open as soon as the pressure on the blowing side of the valve equals the working or receiver pressure and to close as soon as the blowing-piston reaches the limit of its.

stroke and before it begins to recede.

My invention consists in certain novel fea tures of construction which cause these operations to result automatically from the operation of the blowing-engine.

In the accompanying drawings, Figure 1 is a vertical section through a portion of the compression-cylinder of a blowing-engine and the air-discharge valves at opposite ends thereof, the blowing-piston being shown in elevation and the section being taken through the plane of the valve-stems. Fig. 2 is a plan view of one of the air-discharge-valve casings, showing the connections which supply pressure to opposite sides of the valve-piston. Fig. 3 is a vertical sectional detail view showing the pressure communication with the under side of the valve-piston.

1 represents the blowing-cylinder, and 2 the piston working therein. 40

3 represents the air-discharge valves located at opposite ends of the cylinder 1 and with the operation of which my present invention is concerned. These valves should open when the pressure on the cylinder side is equal to the pressure on the receiver side thereof, and they should close at the instant the piston 2 reaches the end of its stroke. These valves are controlled by pistons 5, working in cylinders 6, and these controlling means are identical in construction, except that the upper one employs the influence of gravity in its operation and has a dash -pot or cushioningchamber 7 at top to check the opening action,

while the lower valve has a spring 8, with an adjustable seat'9, that pressesupon the piston in the direction of closing the valve, and this spring is adjusted to such tension as will not. only overcome the tendency of gravitation in the valve in. the direction of opening, but will exert pressure in the direction of closing equal to the load which is imposed by gravity upon the upper valve in the direction of closing. Each valve is supplied with pressure from the blow-cylinder by a pipe 10, which opens into the blowing-cylinder at a point 11, which is between the limits of movement of the piston.

"2, but is also near enough to the end of the cylinder to receive pressure from in front of the advancing piston equal to the pressure on the receiving side of the valve and yet far enough from the end of the cylinder to permit the piston to move beyond the said opening 11 and bring the pipe 10 into communication with the suction side of the piston. The pipe 10 is thus adapted to communicate pressure and to exhaust the same, and it is connected with the cylinder 6 in such a manner that the piston 5 is subjected to pressure equal to that on the receiver side of the valve 3 each time the piston 2 makes a compressionstroke and to exhaust such pressure from the piston 5 each time the piston 2 completes its compression-stroke. Communication between the pipe 10 and the cylinder 6 is efl'ected through a branch pipe 12, (shown in Figs. 2 and 3,) leading into a passage 13 14, Fig. 3, into the lower end of the cylinder 6, which is beneath the valve-piston 5. The pipe 10 also communicates with the cylinder 6 through a branch 15 and a port 16, Fig. 1. The branch 12, as shown in Fig. 2, contains a check-valve 17 which prevents return of pressure medium or relief of pressure back through the branch 12. Hence it follows that when the piston 5 is lifted. by the communication of pressure beneath it and then is permitted to return by the exhaust of said pressure through the port 16 and the branch 15 a body of -air suificient to cushion the piston will be trapped below the port 16.

The upper portion of the valve-piston 5 is reduced to leave an annular chamber 18 between it and the cylinder 6, to the upper portion of which chamber pressure is communicated through a pipe 19, leading from the receiver 4. The upper portion of the piston 5 is thus subjected constantly to the receiver or service pressure of the engine. The reduced portion of the piston 5 works through a packing 20, located above the chamber 18, and between the packing 20 and the cushionchamber 7 is a chamber 21, open to the atmosphere by ports 22 and larger in diameter than the cushion-chamber. This construction permits the piston 5 to make a portion of its movement without being im pededthat is,the first part of the opening movementwhile the end of the opening movement only is cushioned.

It will be seen that by the influence of gravity on the upper valve and of the spring 8 on the lower valve each valve, with the parts connected with it, is normally biased to its closed position. As the piston 2 moves toward either end it develops on the blowing side of the valve pressure equal to that on the receiver side of the valve, which practically balances the valve so far as concerns the pressure immediately imposed upon it; but this pressure is communicated through pipe 10 to the under side of the valve-piston 5, the area of which thus subjected to the pressure is sufficient to cause the valve-piston to raise the valve in opposition to the weight of the valve or the pressure of the spring 8, according to the valve being considered, and also in opposition to the receiver pressure exerted through pipe 19 in the restricted annular chamber 18. The valve is thus opened at the moment that the receiver-pressure is equaled on the pumping side of the valve; but as soon as the piston 2 passes the opening 11 pressure is immediately exhausted from beneath the piston in the cylinder'6, and said piston and the valve 3 consequently descend under gravitation or spring-pressure, assisted by receiver-pressure in the chamber 18; but, the escape of air taking place through the ports 16, (its escape being prevented through the branch 12 by the check-valve 17,) sufficient air will be trapped in the cylinder 6 below the ports 16 to effectually cushion the action of the parts. Cushioning in the other directionthe direction of opening the valveis accomplished by the dash-pot 7 in the upper valve and the spring 8 in the lower valve.

The gravitation of the upper valve and the spring-pressure in the lower valve are employed primarily for seating the valves when the engine is not in use. They serve their functions while the engine is used, and the area of the upper portion of the valve-piston subjected to pressure in the chamber 18 is determined accordingly. It is obvious, however, that the omission of this gravitation or pressure-spring feature and the dependence on the receiver-pressure above the valve-piston to close the valve would not be a material departure from the spirit of my invention, for the constant receiver-pressure might be employed alone to bias the valves toward closed position.

Having thus described the invention, the following is what I claim as new therein:

1. In a blowing-engine, the combination of an air-discharge valve, a piston working in a cylinder and controlling said valve, a pipe supplying pressure to said cylinder at a point beneath the same, means opposing the exhausting of said pressure at such point, and a branch pipe communicating between the pressure-pipe and thecylinder at a point above the lowerdimit of the piston, through which pressure is exhausted from the cylinder; said valve being biased to closed position.

2. In a blowing-engine, the combination of the air-discharge valve, a piston. working in a cylinder and having controlling connection with said valve, a pipe provided with a backpressure valve and supplying pressure to a point on one side of the valve-piston from a point between the limits of the movement of the blowing-engine piston of the main compression-cylinder ot' the engine, a port for exhausting pressure from said valve-piston at a different point in the cylinder from that which itenters, and a pipe supplying receiverpressure to the cylinder at a point on the other side of the valve-piston.

3. In a blowing-engine, the combination of an air-discharge valve, a piston working in a cylinder and having controlling connection with said valve, and biased in the direction of closing the valve, an air-cushion chamber for ALEXANDER K. RARIG.

In presence of GEo. J. CAssADY, W. E. WEEKS. 

